import math
x1,y1,x2,y2=map(float,input().split())
x2=x2-x1
y2=y2-y1
x1,y1=0,0
dis=(x2**2+y2**2)
print(math.sqrt(dis)) import math math x1,y1,x2,y2=map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 x2=x2-x1 x2 x2-x1 x2 x1 y2=y2-y1 y2 y2-y1 y2 y1 x1,y1=0,0 x1 0 y1 0 dis=(x2**2+y2**2) dis x2**2+y2**2 x2**2 x2 2 y2**2 y2 2 print(math.sqrt(dis)) print math.sqrt(dis) math.sqrt math sqrt dis y1,x2,y2=map(float,input().split()) map(float,input().split()) y1 x2,y2=map(float,input().split()) map(float,input().split()) x2 x1,y1,x2,y2=map(float,input().split()) map(float,input().split()) x1 dis=(x2**2+y2**2) x2**2+y2**2 dis y2=map(float,input().split()) map(float,input().split()) y2 x1,y1=0,0 0 x1 x2=x2-x1 x2-x1 x2 y2=y2-y1 y2-y1 y2 y1=0,0 0 y1
import math
x1,y1,x2,y2=map(float,input().split())
x2=x2-x1
y2=y2-y1
x1,y1=0,0
dis=(x2**2+y2**2)
print(math.sqrt(dis))